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Abstract:

When a touching object has touched a touch panel, a reference point
position RP, a dead zone DZ, and a scroll target position SP* are set
based on a touch position TP (S110 to S130); when the touch position TP
has moved outside the dead zone DZ, the scroll target position SP* is
updated with the touch position TP (S200) and unit scroll control is
executed to control a display such that the reference point position RP
moves toward the scroll target position SP* (a displayed image is
scrolled) (S220); wherein, when the touch position TP has moved outside
the dead zone DZ, the dead zone DZ is updated such that the position
between the touch position TP and the reference point position RP just
before the unit scroll control is executed becomes the center position of
the dead zone DZ (S230).

Claims:

1. A display device including a display unit that displays an image on an
image display surface and a touch panel that detects a touched position
of a touching object, the touch panel being installed on the image
display surface of the display unit, comprising: a dead zone setting unit
that, when the touching object has touched the touch panel, sets as a
dead zone an area including a touched position of the touching object on
the touch panel as a center position of the set area; a scroll target
position setting unit that, when the touching object has not moved
outside the set dead zone with the touch panel being touched, holds a
scroll target position serving as a target position of scroll of a
displayed image that is an image displayed on the image display surface,
and when the touching object has moved outside the set dead zone with the
touch panel being touched, updates the scroll target position with the
touched position of the touching object on the touch panel; and a scroll
controlling unit that controls the display unit such that the displayed
image is scrolled according to the set scroll target position, wherein
the dead zone setting unit, when the touching object has moved outside
the set dead zone with the touch panel being touched, updates the dead
zone such that an intermediate position becomes the center position of
the dead zone, the intermediate position being a position between the
touched position of the touching object on the touch panel and the center
position of the set dead zone.

2. The display device according to claim 1, comprising a display
reference point setting unit that, when the touching object has touched
the touch panel, sets as a display reference point a position in the
displayed image corresponding to the touched position of the touching
object on the touch panel, wherein the scroll controlling unit is a unit
that repeatedly executes unit scroll control to control the display unit
such that a reference point position that is a position on the display
unit corresponding to the set display reference point is moved toward the
set scroll target position by a distance shorter than a distance between
the reference point position and the set scroll target position when
scrolling the displayed image, and the dead zone setting unit is a unit
that updates the center position of the dead zone using the reference
point position that was moved through an execution of the unit scroll
control as the intermediate position.

3. The display device according to claim 2, wherein the scroll control
unit is a unit that controls the display unit, as the unit scroll
control, such that the reference point position is moved toward the set
scroll target position by a predetermined rate of the distance between
the set scroll target position and the reference point position.

4. The display device according to claim 1, wherein the dead zone setting
unit is a unit that, after the touching object has moved outside the set
dead zone with the touch panel being touched, updates the dead zone such
that the intermediate position that gradually moves toward the set scroll
target position becomes the center position of the dead zone.

5. The display device according to claim 4, comprising a display
reference point setting unit that, when the touching object has touched
the touch panel, sets as a display reference point a position in the
displayed image corresponding to the touched position of the touching
object on the touch panel, wherein the scroll controlling unit is a unit
that repeatedly executes unit scroll control to control the display unit
such that a reference point position that is a position on the display
unit corresponding to the set display reference point is moved toward the
set scroll target position by a distance shorter than a distance between
the reference point position and the set scroll target position when
scrolling the displayed image.

6. The display device according to claim 5, wherein the scroll
controlling unit is a unit that controls the display unit, as the unit
scroll control, such that the reference point position accords to the
center position of the set dead zone.

7. A control method of a display device including a display unit that
displays an image on an image display surface and a touch panel that
detects a touched position of a touching object, the touch panel being
installed on the image display surface of the display unit, comprising
the steps of: (a) when the touching object has touched the touch panel,
setting as a dead zone an area including a touched position of the
touching object on the touch panel as a center position of the set area;
(b) when the touching object has not moved outside the set dead zone with
the touch panel being touched, holding a scroll target position serving
as a target position of scroll of a displayed image that is an image
displayed on the image display surface, and when the touching object has
moved outside the set dead zone with the touch panel being touched,
updating the scroll target position with the touched position of the
touching object on the touch panel; and (c) controlling the display unit
such that the displayed image is scrolled according to the set scroll
target position, wherein the step (a) is a step of updating, when the
touching object has moved outside the set dead zone with the touch panel
being touched, the dead zone such that an intermediate position becomes
the center position of the dead zone, the intermediate position being a
position between the touched position of the touching object on the touch
panel and the center position of the set dead zone.

8. A program causing a computer to execute the steps of the control
method of the display device of claim 7.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a display device, a control method
and a program of the display device.

BACKGROUND ART

[0002] Conventionally, display devices are being proposed, which are
provided with an image display part that performs image display and a
coordinate input part (a touch panel) installed on a front surface of the
image display part, and when getting in a touch status due to the
occurrence of input data from the coordinate input part through a touch
on the touch panel, performs control to scroll a screen based on a change
vector of an input coordinate given as the input data (for example, refer
to PTL1). These devices repeatedly perform control to scroll the screen
by a changed amount according to a change vector of the input coordinate.

CITATION LIST

Patent Literature

[0003] PTL1: Japanese Patent Laid-Open No. H10-161628

SUMMARY OF INVENTION

Technical Problem

[0004] In recent years, in order to prevent the screen from being scrolled
along with an unintended movement of a touched position (the input
coordinate) of a touching object such as a finger, a pen, or the like, it
is studied to set a dead zone including the input coordinate as a center
position when the touching object has started to touch the touch panel so
that the screen is not scrolled while the input coordinate is within the
dead zone later. In case of scrolling the screen according to the input
coordinate using this technology, a target position of scroll on a screen
is not updated if the input coordinate is inside the dead zone, and the
target position is updated with the input coordinate if the input
coordinate is outside the dead zone and the screen is scrolled toward the
finally-updated target position. In this case, when the input coordinate
has moved outside the dead zone, if the dead zone is updated such that
the moved input coordinate becomes the center position of the dead zone,
the time until the input coordinate moves outside the dead zone next
after the dead zone has been updated becomes relatively long and the
updating frequency of the target position of scroll decreases, which
could make the screen scroll nonsmooth.

[0005] It is a main object of the display device, the control method and
the program of the display device to realize a smoother scroll when
scrolling the displayed image.

Solution to Problem

[0006] To achieve the aforementioned main object, the display device, the
control method and the program of the display device according to the
present invention apply the following means.

[0007] A display device according to the present invention, including a
display unit that displays an image on an image display surface and a
touch panel that detects a touched position of a touching object, the
touch panel being installed on the image display surface of the display
unit, includes: a dead zone setting unit that, when the touching object
has touched the touch panel, sets as a dead zone an area including a
touched position of the touching object on the touch panel as a center
position of the set area; a scroll target position setting unit that,
when the touching object has not moved outside the set dead zone with the
touch panel being touched, holds a scroll target position serving as a
target position of scroll of a displayed image that is an image displayed
on the image display surface, and when the touching object has moved
outside the set dead zone with the touch panel being touched, updates the
scroll target position with the touched position of the touching object
on the touch panel; and a scroll controlling unit that controls the
display unit such that the displayed image is scrolled according to the
set scroll target position, wherein the dead zone setting unit, when the
touching object has moved outside the set dead zone with the touch panel
being touched, updates the dead zone such that an intermediate position
becomes the center position of the dead zone, the intermediate position
between the touched position of the touching object on the touch panel
and the center position of the set dead zone.

[0008] In the display device according to the present invention, when the
touching object has touched the touch panel, the area including the
touched position of the touching object on the touch panel at the center
position is set as the dead zone; when the touching object has not moved
outside the dead zone with the touch panel being touched, the scroll
target position serving as a target position of scroll of the displayed
image that is the image displayed on the image display surface is held,
and when the touching object has moved outside the dead zone with the
touch panel being touched, the scroll target position is updated with the
touched position of the touching object on the touch panel; and the
display unit is controlled such that the displayed image is scrolled
according to the set scroll target position, wherein, when the touching
object has moved outside the currently-set dead zone with the touch panel
being touched, the dead zone is updated such that the intermediate
position that is a position between the touched position of the touching
object on the touch panel and the center position of the currently-set
dead zone becomes the center position of the dead zone. Thereby, compared
to updating the dead zone such that the touched position of the touching
object on the touch panel becomes the center position of the dead zone
when the touching object has moved outside the currently-set dead zone
with the touch panel being touched, it becomes difficult that the touched
position of the touching object enters the dead zone, and the time until
the touched position of the touching object moves outside the dead zone
next becomes short when the touching object is moving with the touch
panel being touched. Therefore, it is possible to make the movement of
the scroll target position smoother by increasing the updating frequency
of the scroll target position based on the touched position of the
touching object. As a result, it becomes possible to make the scroll of
the displayed image based on the scroll target position smoother.

[0009] In the above-mentioned display device according to the present
invention, the display device may include a display reference point
setting unit that, when the touching object has touched the touch panel,
sets as a display reference point a position in the displayed image
corresponding to the touched position of the touching object on the touch
panel, wherein the scroll controlling unit is a unit that repeatedly
executes unit scroll control to control the display unit such that a
reference point position that is a position on the display unit
corresponding to the set display reference point is moved toward the set
scroll target position by a distance shorter than a distance between the
reference point position and the set scroll target position when
scrolling the displayed image, and the dead zone setting unit is a unit
that updates the center position of the dead zone using the reference
point position that was moved through an execution of the unit scroll
control as the intermediate position. In this manner, it is possible to
make the display reference point difficult to be hidden by the touching
object or the like, because the reference point position moves following
the movement of the scroll target position when the scroll target
position is moving. In addition, it is possible to make the touched
position of the touching object difficult to enter the dead zone when the
touching object is moving with the touch panel being touched, because the
dead zone moves following the movement of the touching object. In the
display device according to the present invention having the above
configuration, the scroll control unit may be a unit that controls the
display unit, as the unit scroll control, such that the reference point
position is moved toward the set scroll target position by a
predetermined rate of the distance between the set scroll target position
and the reference point position. Here, the "predetermined rate" may be a
rate that is more than a value 0 but less than a value 1, for example,
0.4, 0.5, 0.6, or the like, of the distance between the scroll target
position and the reference point position.

[0010] In the display device according to the present invention, the dead
zone setting unit may be a unit that, after the touching object has moved
outside the set dead zone with the touch panel being touched, updates the
dead zone such that the intermediate position that gradually moves toward
the set scroll target position becomes the center position of the dead
zone. In such manner, it is possible to make the touched position of the
touching object difficult to enter the dead zone when the touching object
is moving with the touch panel being touched, because the dead zone moves
following the movement of the touching object. In the display device
according to the present invention having the above configuration, the
display device may include a display reference point setting unit that,
when the touching object has touched the touch panel, sets as a display
reference point a position in the displayed image corresponding to the
touched position of the touching object on the touch panel, wherein the
scroll controlling unit is a unit that repeatedly executes unit scroll
control to control the display unit such that a reference point position
that is a position on the display unit corresponding to the set display
reference point is moved toward the set scroll target position by a
distance shorter than a distance between the reference point position and
the set scroll target position when scrolling the displayed image. In
such manner, it is possible to make the display reference point difficult
to be hidden by the touching object or the like because the display
reference point moves following the movement of the scroll target
position when the scroll target position is moving. In the display device
according to the present invention having the above configuration, the
scroll controlling unit may be a unit that controls the display unit, as
the unit scroll control, such that the reference point position accords
to the center position of the set dead zone.

[0011] A control method of a display device according to the present
invention, the control method of the display device including a display
unit that displays an image on an image display surface and a touch panel
that detects a touched position of a touching object, the touch panel
being installed on the image display surface of the display unit,
includes the steps of: (a) when the touching object has touched the touch
panel, setting as a dead zone an area including a touched position of the
touching object on the touch panel as a center position of the set area;
(b) when the touching object has not moved outside the set dead zone with
the touch panel being touched, holding a scroll target position serving
as a target position of scroll of a displayed image that is an image
displayed on the image display surface, and when the touching object has
moved outside the set dead zone with the touch panel being touched,
updating the scroll target position with the touched position of the
touching object on the touch panel; and (c) controlling the display unit
such that the displayed image is scrolled according to the set scroll
target position, wherein the step (a) is a step of updating, when the
touching object has moved outside the set dead zone with the touch panel
being touched, the dead zone such that an intermediate position becomes
the center position of the dead zone, the intermediate position being a
position between the touched position of the touching object on the touch
panel and the center position of the set dead zone.

[0012] In the control method of the display device according to the
present invention, when the touching object has touched the touch panel,
the area including the touched position of the touching object on the
touch panel as the center position of the set area is set as the dead
zone; when the touching object has not moved outside the dead zone with
the touch panel being touched, the scroll target position serving as the
target position of scroll of the displayed image that is an image
displayed on the image display surface is held, and when the touching
object has moved outside the dead zone with the touch panel being
touched, the scroll target position is updated with the touched position
of the touching object on the touch panel; and the display unit is
controlled such that the displayed image is scrolled according to the set
scroll target position, wherein, when the touching object has moved
outside the set dead zone with the touch panel being touched, the dead
zone is updated such that an intermediate position becomes the center
position of the dead zone, the intermediate position being a position
between the touched position of the touching object on the touch panel
and the center position of the set dead zone. Thereby, compared to
updating the dead zone such that the touched position of the touching
object on the touch panel becomes the center position of the dead zone
when the touching object has moved outside the currently-set dead zone
with the touch panel being touched, it becomes difficult that the touched
position of the touching object enters the dead zone and the time until
the touched position of the touching object moves outside the dead zone
next becomes short when the touching object is moving with the touch
panel being touched. Therefore, it is possible to make the movement of
the scroll target position smoother by increasing the updating frequency
of the scroll target position based on the touched position of the
touching object. As a result, it becomes possible to make the scroll of
the displayed image based on the scroll target position smoother.

[0013] A program according to the present invention causes a computer to
execute the respective steps of the above-mentioned control method of the
display device. The program may be recorded in a storage medium (for
example, a hard disk, a flash memory, a ROM, a CD, a DVD, or the like)
capable of reading the computer, or may be transmitted from a computer to
another computer via a transmission medium (communication network such as
an Internet, a LAN and the like). The program can be transmitted in any
manners. By causing the computer to execute the program, the same effects
as the control method of the display device can be obtained because the
respective steps of the above mentioned control method of the display
device are executed.

BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 is a block diagram illustrating schematic structure of a
navigation device 20 as a display device according to an embodiment of
the present invention.

[0015] FIG. 2 is a flow chart showing an example of a scroll control
routine to be executed by an electric control unit 30.

[0016] FIG. 3 illustrates an example of processings at Step S100 to S130
when a touching object has started to touch a touch panel 24.

[0017] FIGS. 4A, 4B, and 4C illustrate an example of processings at Step
S200 to S230 when a touch position TP is outside a dead zone DZ.

[0018] FIG. 5 schematically illustrates transition of the touch position
TP, a scroll target position SP*, a reference point position RP, a dead
zone DZ according to time-shift when the touching object such as a
finger, a pen, or the like moves at a constant speed with the touch panel
24 being touched.

[0019] FIG. 6 illustrates an example of the transition of the touch
position TP and the reference point position RP according to time shift
when the touching object such as a finger, a pen, or the like moves with
the touch panel 24 being touched.

[0020] FIG. 7 is a flow chart showing an example of the scroll control
routine according to a modification example.

[0021] FIG. 8 is a flow chart showing another example of the scroll
control routine according to the modification example.

DESCRIPTION OF EMBODIMENTS

[0022] The present invention is described in further detail below with
reference to an embodiment.

[0023] FIG. 1 is a block diagram illustrating schematic structure of a
navigation device 20 as a display device according to an embodiment of
the present invention. As shown in FIG. 1, the navigation device 20 is
provided with a display 22 including an image display surface 22a, a
touch panel 24 installed on the image display surface 22a of the display
22, an electric control unit 30 that controls overall device, and a hard
disk drive (hereinafter, referred to as HDD) 40 as a large capacity
memory that stores various kinds of application software, map data, and
the like. The navigation device 20 is operated upon receiving power
supply from an in-vehicle battery mounted on a vehicle (not shown).

[0024] The display 22 is, for example, a liquid crystal display that
includes a rectangular-shaped image display surface 22a to display
letters and images. The touch panel 24 is a touch panel that detects a
touch position TP that is a touched position of a touching object such as
a finger, a pen, or the like on the touch panel. In addition, as a
detection method of the touch position TP by the touch panel 24, a
resistive method, a capacitance method, an infrared method, an
electromagnetic induction method, a surface acoustic wave method, or the
like can be utilized.

[0025] The electric control unit 30 is a micro processor having a CPU 32
at the center. The electric control unit 30 is provided with, in addition
to the CPU 32, a ROM 34 that stores various kinds of processing programs,
a RAM 36 that temporarily stores data, a nonvolatile flash memory that
holds the stored data, and an input-output port and a communication port
(not shown). Into the electric control unit 30, the touch position TP
from the touch panel 24, the data read from the HDD 40, signals from a
GPS receiver 50 that receives signals from a GPS (Global Positioning
System) satellite via a GPS antenna, signals from a direction sensor 52
that is, for example, a gyro sensor detecting a travel direction of the
vehicle and its change, and the like are inputted via the input port.
From the electric control unit 30, display signals to the display 22,
audio signals to a speaker 26 equipped with an amplifier, data to write
into the HDD 40, and the like are outputted via the output port. In
addition, the electric control unit 30 is connected to a vehicular
electric control unit (not shown) that controls the overall vehicle via
the communication port. The electric control unit 30 inputs the data
regarding the status of the vehicle by communication as well as outputs
data regarding the status of the navigation device 20 as needed.

[0026] In the navigation device 20 according to the embodiment, the
electric control unit 30 reads necessary application software and map
data from the HDD 40 and executes various kinds of processing. For
example, the electric control unit 30 executes processings such as a
location processing that determines a current position of the vehicle
based on the signals from the GPS receiver 50 and the signals from the
direction sensor 52, a map display processing that displays a map image
including roads on the display 22, a destination input processing that
inputs a destination based on an operation on the touch panel 24 by an
operator, a navigation processing that searches for a travel route to the
destination and provides route guidance by a map display and by audio
output from the speaker 26.

[0027] Next, the operation of the navigation device 20 configured as above
as the display device in the embodiment, especially the operation of
scrolling a displayed image that is an image displayed on the display 22
along with a movement of a touching object when the operator has moved
the touching object such as a finger, a pen, or the like keeping the
touch on the touch panel 24 (i.e., when the operator has performed a drag
operation) is explained. FIG. 2 is a flow chart showing an example of a
scroll control routine to be executed by the electric control unit 30.
The routine starts to be executed when the touching object has touched
the touch panel 24 (the touching object has started to touch the touch
panel 24).

[0028] When the scroll control routine has been executed, the CPU 32 of
the electric control unit 30 firstly acquires the touch position TP from
the touch panel 24 (Step S100), sets as a display reference point the
position on the displayed image corresponding to the acquired touch
position TP (Step S110), sets a dead zone DZ (a zone where a touch is not
detected) including the touch position TP at the center position (Step
S120), and sets the touch position TP as a scroll target position SP*
that is a target position of scroll on the displayed image (Step S130).
Here, the display reference point is a position on the displayed image
(for example, XX station, YY company, ZZ school, and the like). The touch
position TP, a reference point position RP that is a position on the
image display surface 22a corresponding to the display reference point,
the center position of the dead zone DZ, the scroll target position SP*
are positions on the touch panel 24 or the image display surface 22a (for
example, a coordinate (x, y) of XY coordinate format having X direction
in a horizontal direction and Y direction in a vertical direction)
respectively. Consequently, when the displayed image is scrolled, the
position on the displayed image as the display reference point does not
move, but the position on the image display surface 22a as the reference
point position RP moves. In addition, the dead zone DZ is set to prevent
the displayed image from being scrolled along with an unintended movement
of the touched position of the touching object on the touch panel 24 when
the touched position has unintentionally moved with the touch panel 24
being touched by the touching object. In the embodiment, the dead zone DZ
is set with an area (a circular area) within a predetermined distance
(for example, a distance corresponding to 3 dots, 5 dots, and 7 dots of
the display 22) from the center position. The processings at Step S110 to
S130 are processings to set the reference point position RP (the position
on the image display surface 22a corresponding to the display reference
point), the dead zone DZ, and the scroll target position SP* based on the
touch position TP when the touching object has started to touch the touch
panel 24. Hereinafter, the touch position TP, the reference point
position RP, the dead zone DZ, and the scroll target position SP* at this
moment are referred to as an initial touch position TP0, an initial
reference point position RP0, an initial dead zone DZ0, and an initial
scroll target position SP0, respectively.

[0029] FIG. 3 illustrates an example of the processings at Step S100 to
S130 when the touching object has started to touch the touch panel 24. In
FIG. 3, the upper figure shows the status of the image display surface
22a, and the lower figure is an enlarged view of the area bordered by a
dotted line in the upper figure. The lower figure in FIG. 3 is an
enlarged view of a partial area (the area bordered by four coordinates of
the above-mentioned XY coordinate format (x1, y1), (x2, y1), (x1, y2),
and (x2, y2) on the image display surface 22a to explain the touch
position TP, the dead zone DZ, and the like. As seen from FIG. 3, the
touch position TP, the reference point position RP, the scroll target
position SP* accord and the dead zone DZ having the same position at the
center position is set. Note that the touch position TP, the reference
point position RP, the dead zone DZ, and the scroll target position SP*
are conceptual and not displayed on the actual image display surface 22a.

[0030] Subsequently, the CPU 32 determines whether the touching object is
touching the touch panel 24 (Step S140). If it has been determined that
the touching object is not touching the touch panel 24, the CPU 32
terminates the routine. The determination of whether the touching object
is touching the touch panel 24 can be performed by examining whether
there is an input of the touch position TP from the touch panel 24.

[0031] If it has been determined that the touching object is touching the
touch panel 24, the CPU 32 acquires the touch position TP from the touch
panel 24 (Step S150) and determines whether the acquired touch position
TP is inside or outside the dead zone DZ (Step S160, S170). If it has
been determined that the touch position TP is inside the dead zone DZ,
the CPU 32 does not update (hold) the scroll target position SP*, and
determines whether the scroll target position SP* and the reference point
position RP approximately accord (Step S180, S190). The determination at
Step S180 and S190 is processings to determine whether it is necessary to
scroll the displayed image. In the embodiment, the CPU 32 compares the
distance between the scroll target position SP* and the reference point
position RP with a smallest movement amount (for example, a distance
corresponding to 1 dot of the display 22 or the like) as a smallest value
for the movement amount of the reference point position RP that can be
moved through an execution of unit scroll control, which is described
later. When the distance between the scroll target position SP* and the
reference point position RP is equal to or more than the smallest
movement amount, the CPU 32 determines that the scroll target position
SP* and the reference point position RP do not approximately accord. When
the distance between the scroll target position SP* and the reference
point position RP is less than the smallest movement amount (including a
value 0), the CPU 32 determines that the scroll target position SP* and
the reference point position RP approximately accord.

[0032] When it has been determined that the scroll target position SP* and
the reference point position RP approximately accord, the CPU 32 judges
that it is not necessary to scroll the displayed image and returns to
Step S140 without scrolling the displayed image (without moving the
reference point position RP). It is assumed that the touch position TP
has not moved outside the dead zone DZ (the initial dead zone DZ0) since
the touching object has started to touch the touch panel 24. When the
touching object has started to touch the touch panel 24, the touch
position TP, the reference point position RP, and the scroll target
position SP* (the initial touch position TP0, the initial reference point
position RP0, the initial scroll target position SP0) approximately
accord (refer to the lower figure in FIG. 3). When the touch position TP
has not moved outside the dead zone DZ (the initial dead zone DZ0) from
such state, the scroll target position SP* is not updated (is held).
Therefore, the state where the reference point position RP and the scroll
target position SP* approximately accord continues. Consequently, it is
possible to prevent the displayed image from being scrolled, for example,
when the touching object has unintentionally moved in the vicinity of the
initial touch position TP0.

[0033] When it has been determined at Step S160 and S170 that the touch
position TP is outside the dead zone DZ, the CPU 32 updates the scroll
target position SP* with the touch position TP acquired at Step S140
(Step S200). When the scroll target position SP* has been updated by this
processing, or when it has been determined at Step S180 and S190 that the
scroll target position SP* and the reference point position RP do not
approximately accord, the CPU 32 judges that it is necessary to scroll
the displayed image. Thereafter, the CPU 32 sets a unit target scroll
amount S* that is a target amount of scroll of the displayed image for
one scroll based on the scroll target position SP* and the reference
point position RP (Step S210). The CPU 32 executes the unit scroll
control to control the display 22 such that the reference point position
RP is moved toward the scroll target position SP* (the displayed image is
scrolled) by the set unit target scroll amount S* (Step S220), updates
the dead zone DZ such that the reference point position RP moved through
an execution of the unit scroll control becomes the center position of
the dead zone DZ (Step S230), and returns to Step S140. FIGS. 4A, 4B, and
4C illustrate an example of the processings at Step S200 to S230 when the
touch position TP is outside the dead zone DZ. FIGS. 4A, 4B, and 4C show
the displayed image of the same area in the image display surface 22a as
the area shown in the lower drawing in FIG. 3. As seen from FIGS. 4A, 4B,
and 4C, when the touch position TP is outside the dead zone DZ, the CPU
32 updates the scroll target position SP* with the touch position TP
(refer to FIG. 4A). Thereafter, the CPU 32 executes the unit scroll
control such that the reference point position RP is moved toward the
scroll target position SP* (the displayed image is scrolled) (refer to
FIG. 4B), and updates the dead zone DZ such that the reference point
position RP moved through an execution of the unit scroll control becomes
the center position of the dead zone DZ (refer to FIG. 4C). Hereinafter,
the processing (Step S210) to set the unit target scroll amount S*, the
processing (Step S220) to execute the unit scroll control, and the
processing (Step S230) to update the dead zone DZ are sequentially
explained below.

[0034] First, the processings (Step S210, S220) to set the unit target
scroll amount S* based on the scroll target position SP* and the
reference point position RP and to execute the unit scroll control that
controls the display 22 such that the reference point position RP is
moved (the displayed image is scrolled) toward the scroll target position
SP* by the set unit target scroll amount S* are explained. In the
embodiment, the unit target scroll amount S* is set to a value that is
acquired by multiplying the distance between the scroll target position
SP* and the reference point position RP by a factor k (for example, 0.4,
0.5, 0.6, or the like) that is larger than 0 but smaller than 1.
Consequently, by the unit scroll control, the displayed image is scrolled
such that the reference point position RP is moved toward the scroll
target position SP* by a distance shorter than the distance between the
scroll target position SP* and the reference point position RP. Thereby,
when the scroll target position SP* is moved (is updated), the displayed
image is scrolled such that the reference point position RP moves
following the movement of the scroll target position SP* every time the
unit scroll control is executed. In addition, when the scroll target
position SP* is not moved (is held), the displayed image is scrolled such
that the reference point position RP gradually comes close to the scroll
target position SP* every time the unit scroll control is executed. As a
result, it is possible to make the reference point position RP difficult
to be hidden by the touching object, for example, when the touching
object is moving.

[0035] Next, the processing (Step S230) to update the dead zone DZ such
that the reference point position RP moved through an execution of the
unit scroll control is the center position of the dead zone DZ is
explained. Firstly, in the embodiment, as mentioned above, the unit
scroll control is executed using the unit target scroll amount S*.
Therefore, the reference point position RP just after the unit scroll
control is executed is a position by the unit target scroll amount S*
close to the scroll target position SP* in relation to the reference
point position RP just before the unit scroll control is executed. In
addition, as mentioned above, the unit target scroll amount S* is a
distance shorter than the distance between the scroll target position SP*
and the reference point position RP. Thereby, it can be seen that the
center position of the dead zone DZ after update (the reference point
position RP just after the unit scroll control is executed) is the
position between the scroll target position SP* and the center position
(the reference point position just before the unit scroll control is
executed) of the dead zone DZ before update. Here, when considering that
the scroll target position SP* is updated with the touch position TP in
case that the touch position TP is outside the dead zone DZ, it can be
seen that, just after the touch position TP has moved outside the dead
zone DZ, the center position of the dead zone DZ after update is the
position between the touch position TP and the center position of the
dead zone DZ before update.

[0036] FIG. 5 schematically illustrates the transition of the touch
position TP, the scroll target position SP*, the reference point position
RP, the dead zone DZ according to the time-shift when the touching object
such as a finger, a pen, or the like moves with the touch panel 24 being
touched. In FIG. 5, "t0" indicates a time when the touching object starts
to touch the touch panel 24, the touch position TP (the initial touch
position TP0) is acquired, and the reference point position RP (the
initial reference point position RP0), the dead zone DZ (the initial dead
zone 0), the scroll target position SP* (the initial scroll target
position SP0) are set. In addition, "t11" to "t43" indicate times after
the touching object started to move. The number of the first digit in
"t11" to "43" indicates the time when a series of processings of Step
S140 to S230 were executed. Regarding the number of the second digit in
"t11" to "t43", "1" indicates the time when the touch position TP was
acquired (Step S140), "2" indicates the time when the scroll target
position SP* was updated (Step S200), and "3" indicates the time when the
unit scroll control was executed and the dead zone DZ was updated (Step
S210 to S230). First, when the touching object has started to touch the
touch panel 24, the CPU 32 acquires the touch position TP and sets the
reference point position RP, the dead zone DZ, the scroll target position
SP* (a time t0). When the CPU 32 has acquired the touch position TP (a
time t11), if the acquired touch position TP is inside the dead zone DZ,
the CPU 32 does not update the scroll target position SP*, does not
scroll the displayed image (does not move the reference point position
RP), and does not update the dead zone DZ. Therefore, in FIG. 5, times
t12 and t13 are not shown. On the other hand, when the CPU 32 has
acquired the touch position TP (a time t21), if the acquired touch
position TP is outside the dead zone DZ, the CPU 32 updates the scroll
target position SP* with the acquired touch position TP (a time t22),
executes the unit scroll control based on the updated scroll target
position SP* and the reference point position RP to scroll the displayed
image, and updates the dead zone DZ such that the reference point
position RP moved thereby is the center position of the dead zone DZ (a
time 23). It is assumed that the touching object moves at a constant
speed. Therefore, the next time when the CPU 32 has acquired the touch
position TP (a time t31), if the acquired touch position TP is outside
the dead zone DZ, the CPU 32 sets the scroll target position SP* (a time
t32), executes the unit scroll control to scroll the displayed image, and
updates the dead zone DZ (a time t33) in the same manner as the time t22
and t23. Consequently, the center position (the reference point position
RP) of the dead zone DZ and the dead zone DZ moves following the movement
of the scroll target position SP*. Thereby, when the touching object
moves with the touch panel 24 being touched, it is possible to make the
touch position TP difficult to enter the dead zone DZ, which makes it
possible to more smoothly scroll the displayed image. Thereafter, when
the CPU 32 has acquired the touch position TP (a time t41), if the touch
position TP is inside the dead zone DZ, the CPU 32 does not update the
scroll target position SP* (a time t42). However, if the scroll target
position SP* and the reference point position RP do not approximately
accord, the CPU 32 executes the unit scroll control such that the
reference point position RP moves toward the scroll target position SP*
to scroll the displayed image, and updates the dead zone DZ (a time t43).

[0037] Here, it is assumed that the touching object such as a finger, a
pen, or the like moves at a constant speed with the touch panel 24 being
touched. First, when the touching object touches the touch panel 24, the
CPU 32 sets the reference point position RP (the initial reference point
position RP0), the dead zone DZ (the initial dead zone DZ0), and the like
based on the touch position TP (the initial touch position TP0).
Thereafter, when the touch position TP moves outside the dead zone DZ, if
the CPU 32 updates the dead zone DZ such that the touch position TP
becomes the center position of the dead zone DZ (an example for
comparison), the time until the touch position TP moves outside the dead
zone DZ next after the dead zone DZ is updated becomes long. That is, the
time until the touch position TP moves outside the dead zone DZ next
after the dead zone DZ is updated becomes the same as the time until the
initial touch position TP0 moves outside the initial dead zone DZ0. When
the touch position TP is inside the dead zone DZ, the scroll target
position SP* is not updated. Therefore, the updating frequency of the
scroll target position SP* decreases although the touching object is
moving at the constant speed. When the updating frequency of the scroll
target position SP* is low (is likely to be held), the movement of the
scroll target position SP* becomes nonsmooth. Thereby, the scroll of the
displayed image (the movement of the reference point position RP) based
on the scroll target position SP* could be nonsmooth. On the other hand,
in the embodiment, when the touch position TP moves outside the dead zone
DZ, the CPU 32 updates the dead zone DZ such that the position between
the touch position TP (the scroll target position SP*) and the center
position of the current dead zone DZ (the reference point position RP
just before the unit scroll control is executed) becomes the center
position of the dead zone DZ. Therefore, when the touching position TP is
moving, it becomes difficult that the touch position TP that is firstly
acquired after the dead zone DZ is updated enters the dead zone DZ, and
the time until the touch position TP moves outside the dead zone DZ next
after the dead zone DZ is updated becomes short. Thereby, when the
touching object moves with the touch panel 24 being touched, it is
possible to make the movement of the scroll target position SP* smoother
by increasing the updating frequency of the scroll target position SP*.
Therefore, it becomes possible to make the scroll of the displayed image
based on the scroll target position SP* smoother.

[0038] FIG. 6 illustrates an example of the transition of the touch
position TP and the reference point position RP according to the time
shift when the touching object such as a finger, a pen, or the like moves
with the touch panel 24 being touched. In FIG. 6, the upper drawing
illustrates the embodiment in which the dead zone DZ is updated such that
the reference point position RP moved through an execution of the unit
scroll control becomes the center position of the dead zone DZ when the
touch position TP has moved outside the dead zone DZ. The lower drawing
illustrates an example for comparison in which the dead zone DZ is
updated such that the touch position TP becomes the center position of
the dead zone DZ when the touch position TP has moved outside the dead
zone DZ. In addition, in the example of FIG. 6, from the state in which
the touch position TP, the reference point position RP, and the scroll
target position SP* approximately accord (the time t0), the touch
position TP moves at a constant speed slightly slower than the speed at
which the above-mentioned distance (a distance to determine the dead zone
DZ) is moved for a unit of time (times T1 to T10), and thereafter the
touch position TP does not change (times T11 to T13). In the example for
comparison, as mentioned above, because the time until the touch position
TP moves outside the dead zone DZ next after the dead zone DZ is updated
becomes long, the updating frequency of the scroll target position SP*
decreases (the frequency that the scroll target position SP* is held
increases), and thereby the scroll of the displayed image (the movement
of the reference point position RP) can be nonsmooth. On the other hand,
in the embodiment, because it becomes difficult that the touch position
TP that is firstly acquired after the dead zone DZ is updated enters the
dead zone DZ, and the time until the touch position TP moves outside the
dead zone DZ next after the dead zone DZ is updated becomes short, the
updating frequency of the scroll target position SP* increases, and
thereby the scroll of the displayed image (the movement of the reference
point position RP) can be smooth. In both the embodiment and the example
for comparison, after the touch position TP has moved outside the dead
zone DZ, if the touch position TP does not change any more (the times T11
to T13), the displayed image is scrolled such that the reference point
position RP comes close to the finally-set scroll target position SP*.

[0039] According to the navigation device 20 as the display device in the
above-mentioned embodiment, when the touching object such as a finger, a
pen, or the like has touched the touch panel 24, the CPU 32 sets the
reference point position RP, the dead zone DZ including the touch
position TP at the center position, and the scroll target position SP*
based on the touch position TP. When the touch position TP has not moved
outside the dead zone DZ, the CPU 32 does not update the scroll target
position SP*. When the touch position TP has moved outside the dead zone
DZ, the CPU 32 updates the scroll target position SP* with the touch
position TP, and executes the unit scroll control to control the display
22 such that the reference point position RP moves toward the scroll
target position SP* (the displayed image is scrolled). When the touch
position TP has moved outside the dead zone DZ, the CPU 32 updates the
dead zone DZ such that the position between the touch position TP (the
scroll target position SP*) and the reference point position RP just
before the unit scroll control is executed becomes the center position of
the dead zone DZ. Thereby, compared to updating the dead zone DZ such
that the touch position TP becomes the center position of the dead zone
DZ, when the touching object is moving (the touch position TP is moving),
it becomes difficult that the touch position TP enters the dead zone DZ,
and the time until the touch position TP moves outside the dead zone DZ
next becomes short. Therefore, it is possible to make the movement of the
scroll target position SP* smoother by increasing the updating frequency
of the scroll target position SP*. As a result, it become possible to
make the scroll of the displayed image based on the scroll target
position SP* smoother.

[0040] According to the navigation device 20 as the display device in the
embodiment, the CPU 32 executes the unit scroll control to control
display 22 such that the reference point position RP moves (the displayed
image is scrolled) toward the scroll target position SP* using the
distance shorter than the distance between the scroll target position SP*
and the reference point position RP as the unit target scroll amount S*.
That is, when the scroll target position SP* is not moved (is held), the
displayed image is scrolled such that the reference point position RP
gradually comes close to the scroll target position SP*. When the scroll
target position SP* is moved (is updated), the displayed image is
scrolled such that the reference point position RP moves following the
movement of the scroll target position SP*. Therefore, it is possible to
make the reference point position RP difficult to be hidden by the
touching object or the like when the touching object is moving with the
touch panel 24 being touched.

[0041] In the navigation device 20 in the embodiment, an area (a circular
area) within a predetermined distance from the center position is set as
the dead zone DZ. However, a rectangular area having the center position
as a barycenter may be set as the dead zone DZ.

[0042] In the navigation device 20 in the embodiment, the unit scroll
control is executed using a value acquired by multiplying the distance
between the scroll target position SP* and the reference point position
RP by a factor k (0<k<1) as the unit target scroll amount S*.
However, it is only necessary that, when the scroll target position SP*
is not moved (is held), the displayed image is scrolled such that the
reference point position RP gradually comes close to the scroll target
position SP*, and when the scroll target position SP* is moved (is
updated), the displayed image is scrolled such that the reference point
position RP moves following the movement of the scroll target position
SP*. For example, the unit scroll control may be executed using a
predetermined amount smaller than the distance between the reference
point position RP when the scroll target position SP* has been updated
and the scroll target position SP* at such moment (for example, one-Xth
of the distance or the like) as the unit target scroll amount S*.

[0043] In the navigation device 20 in the embodiment, the dead zone DZ is
updated such that the reference point position RP just after the unit
scroll control has been executed using the unit target scroll amount S*
becomes the center position of the dead zone DZ, that is, the dead zone
DZ is updated after the unit scroll control was executed. However,
because it is assumed that the unit target scroll amount S* is the same
as the movement amount of the reference point position RP by an execution
of the unit scroll control, the unit scroll control may be executed using
the unit target scroll amount S* after the dead zone DZ was updated such
that the position on the side of the scroll target position SP* in
relation to the reference point position RP just before the unit scroll
control by the unit target scroll amount S* was executed becomes the
center position of the dead zone DZ.

[0044] In the navigation device 20 in the embodiment, when the touch
position TP is outside the dead zone DZ, the touch position TP is set as
the scroll target position SP* and the unit scroll control is executed
based on the set scroll target position SP* and the reference point
position RP, and the dead zone DZ is updated such that the reference
point position RP moved through an execution of the unit scroll control
becomes the center position of the dead zone DZ. However, the dead zone
DZ may be updated such that a position different from the reference point
position RP moved through an execution of the unit scroll control becomes
the center position of the dead zone DZ. An example of the scroll control
routine in such case is shown in FIG. 7. The routine in FIG. 7 is the
same as the routine in FIG. 2 except that the processing at Step S202 is
added to the routine in FIG. 2 and the processing at Step S230 of the
routine in FIG. 2 is not executed. Consequently, the same step number is
assigned to the same processing and the detailed explanation is omitted.
In the scroll control routine in FIG. 7, when it has been determined at
Step S160 and S170 that the touch position TP is outside the dead zone DZ
and the CPU 32 has updated the scroll target position SP* with the touch
position TP at Step S200, or when it has been determined at Step S160 and
S170 that the touch position TP is inside the dead zone DZ but it has
been determined at Step S180 and S190 that the scroll target position SP*
and the reference point position RP do not approximately accord, the CPU
32 updates the dead zone DZ such that the position between the scroll
target position SP* and the reference point position RP becomes the
center position of the dead zone DZ (Step S202). Thereafter, the CPU 32
sets the unit target scroll amount S* based on the scroll target position
SP* and the reference point position RP (Step S210), executes the unit
scroll control using the set unit target scroll amount S* (Step S220),
and returns to Step S140. Here, in the example of the modification, the
CPU 32 updates the dead zone DZ such that the position on the side of the
scroll target position SP* in relation to the reference point position RP
by the distance that is acquired by multiplying the distance between the
scroll target position SP* and the reference point position RP (the
reference point position RP just before the unit scroll control is
executed) by a factor k2 (for example, 0.4, 0.5, 0.6, or the like) that
is larger than 0 but smaller than 1 becomes the center position of the
dead zone DZ. Consequently, when the touch position TP is outside the
dead zone DZ and the scroll target position SP* is moved (is updated),
the center position of the dead zone DZ gradually moves toward the scroll
target position SP*. In addition, when the touch position TP is inside
the dead zone DZ, the scroll target position SP* is not moved (is held),
and the scroll target position SP* and the reference point position RP do
not approximately accord, the center position of the dead zone DZ
gradually comes close to the scroll target position SP*. Also, in the
example of the modification as the embodiment, compared to updating the
dead zone DZ such that the touch position TP becomes the center position
of the dead zone DZ, when the touching object is moving (the touch
position TP is moving), it becomes difficult that the touch position TP
enters the dead zone DZ, and the time until the touch position TP moves
outside the dead zone DZ next becomes short. Therefore, it is possible to
make the movement of the scroll target position SP* smoother by
increasing the updating frequency of the scroll target position SP*. As a
result, it becomes possible to make the scroll of the displayed image
based on the scroll target position SP* smoother.

[0045] In case of the example of the modification, it is considered that
the movement amount of the center position of the dead zone DZ is not
necessary to be associated with the unit target scroll amount S* (the
scroll amount of the displayed image for one scroll). Therefore, the
distance between the scroll target position SP* and the reference point
position RP may be utilized as the unit target scroll amount S*, that is,
the displayed image may be scrolled in accordance with the movement of
the scroll target position SP* without delay. In the navigation device 20
in the embodiment, the touch position TP is set as the scroll target
position SP*, the unit scroll control is executed using the unit target
scroll amount S* based on the scroll target position SP* and the
reference point position RP, and the dead zone DZ is updated such that
the immediate reference point position RP becomes the center position of
the dead zone DZ. Therefore, if the displayed image is scrolled in
accordance with the movement of the scroll target position SP* without
delay, the dead zone DZ is updated such that the scroll target position
SP* becomes the center position of the dead zone DZ. In this case, as
explained in the embodiment, the displayed image is necessary to be
scrolled such that the reference point position RP moves following the
movement of the scroll target position SP*.

[0046] In case of the example of the modification, it is considered that
the movement of the center position of the dead zone DZ is not necessary
to be associated with the movement of the reference point position RP
through an execution of the unit scroll control (scroll of the displayed
image). Therefore, when it has been determined that the touch position TP
is inside the dead zone DZ, the dead zone DZ may not be updated
regardless of whether the scroll target position SP* and the reference
point position RP accord (in the routine in FIG. 7, when it has been
determined at Step S160 and S170 that the touch position TP is inside the
dead zone DZ and it has been determined at Step S180 and Step S190 that
the scroll target position SP* and the reference point position RP do not
approximately accord, the procedure proceeds to Step S210).

[0047] In addition, in the example of the modification, in the same manner
as the navigation device 20 in the embodiment, the unit scroll control is
executed using the unit target scroll amount S* based on the scroll
target position SP* and the reference point position RP independently of
the center position of the dead zone DZ. However, the dead zone DZ is
updated before executing the unit scroll control in the example of the
modification. Therefore, the unit scroll control may be executed based on
the center position of the dead zone DZ. An example of the scroll control
routine in this case is shown in FIG. 8. The routine in FIG. 8 is the
same as the routine in FIG. 7 except that the processing at Step S201c is
executed in place of the processing at Step S210 of the routine in FIG.
7. Consequently, the same step number is assigned to the same processing
and the detailed explanation is omitted. In the scroll control routine in
FIG. 8, when the CPU 32 updates the dead zone DZ such that the position
between the scroll target position SP* and the reference point position
RP becomes the center position of the dead zone DZ, the CPU 32 sets the
unit target scroll amount S* based on the center position of the dead
zone DZ and the reference point position RP (Step S210c), executes the
unit scroll control using the set unit target scroll amount S* (Step
S220), and returns to Step S140. Here, the unit target scroll amount S*
may be set to the distance between the center position of the dead zone
DZ and the reference point position RP because the center position of the
dead zone DZ is a position between the scroll target position SP* and the
reference point position RP. In this case, if the factor k2 used to set
the center position of the dead zone DZ is the same value as the factor
k1 used to set the unit target scroll amount S*, the movement of the dead
zone DZ and the scroll of the displayed image becomes the same as the
embodiment. In addition, the unit target scroll amount S* may be a value
acquired by multiplying the distance between the center position of the
dead zone DZ and the reference point position RP by a factor k3.

[0048] In the embodiment, the present invention is applied to the
navigation device 20 as the display device. However, the present
invention is not limited to the navigation device 20, and may be applied
to any display devices, provided that the display device includes a
display unit that displays an image on the image display surface and a
touch panel that is installed on the image display surface of the display
unit and detects the touched position of a touching object, for example,
cellular phones, information terminals, copying devices, facsimiles,
printers, home video game machines, and the like.

[0049] In addition, in the embodiment, the present invention is applied to
the navigation device 20 as the display device. However, the present
invention may be applied to a control method of the display device, or a
program to cause a computer to execute the respective steps of the
control method of the display device.

[0050] The correspondence relation between the main elements of the
embodiment and the main elements of the invention described in the
section of the [Means for Solving the Problems] is explained. In the
embodiment, the display 22 corresponds to the "display unit" The touch
panel 24 corresponds to the "touch panel" The electric control unit 30
that executes the processing at Step S110 of the scroll control routine
in FIG. 2 to set the dead zone DZ including the touch position TP at the
center position when the touching object such as a finger, a pen, or the
like has started to touch the touch panel 24 and the processing at Step
230 of the scroll control routine in FIG. 2 to update the dead zone DZ
such that the position between the touch position TP and the reference
point position RP just before the unit scroll control is executed becomes
the center position of the dead zone DZ when the touch position TP is
outside the dead zone DZ corresponds to the "dead zone setting unit". The
electric control unit 30 that executes the processings at Step S170 and
S200 of the scroll control routine in FIG. 2 not to update the scroll
target position SP* when the touch position TP has not moved outside the
dead zone DZ and to update the scroll target position SP* with the touch
position TP when the touch position TP has moved outside the dead zone DZ
corresponds to the "scroll target position setting unit". The electric
control unit 30 that executes the processing at Step S220 of the scroll
control routine in FIG. 2 to execute the unit scroll control to control
the display 22 such that the reference point position RP moves toward the
scroll target position SP* (the displayed image is scrolled) when the
scroll target position SP* and the reference point position RP do not
approximately accord corresponds to the "scroll control unit". In
addition, the electric control unit 30 that executes the processing at
Step S110 of the scroll control routine in FIG. 2 to set the position in
the displayed image corresponding to the touch position TP as the display
reference point when the touching object such as a finger, a pen, or the
like has started to touch the touch panel 24 corresponds to the "display
reference point setting unit".

[0051] The correspondence relation between the main elements of the
embodiment and the main elements of the invention described in the
section of the [Means for Solving the Problems] is an example to
specifically explain the modes in which the embodiment carries out the
invention described in described in the section of the [Means for Solving
the Problems]. Therefore, the elements of the invention described in the
section of the [Means for Solving the Problems] are not limited thereto.
That is, the interpretation of the invention described in the section of
the [Means for Solving the Problems] should be performed based on the
description in the section. Therefore, the embodiment is merely a
specific example of the invention described in the section of the [Means
for Solving the Problems].

[0052] The modes for carrying out the invention are explained using the
embodiment. However, the present invention is not limited to the
embodiment. The present invention is carried out in various kinds of
modes without departing from the broad spirit and scope of the underlying
principles.

[0053] While various features have been described in conjunction with the
examples outlined above, various alternatives, modifications, variations,
and/or improvements of those features and/or examples may be possible.
Accordingly, the examples, as set forth above, are intended to be
illustrative. Various changes may be made without departing from the
broad spirit and scope of the underlying principles.

INDUSTRIAL APPLICABILITY

[0054] The present invention can be utilized for the manufacturing
industry of display devices and the like.